1. Field of the Invention
The present invention relates generally to batteries and in the preferred embodiment to batteries of the bipolar type. Still more particularly, the present invention relates to containment systems for such batteries. In its most preferred embodiment, the present invention relates to a monolithic system for containing a plurality of battery components, including terminal electrodes and one or more battery cells. In its most preferred embodiment, the present invention relates to an injection molded monolithic containment system and a novel spacer.
2. Description of the Prior Art
A number of different systems have been proposed for containing battery components of both the monopolar and bipolar types, all as described in several of the patents which will be discussed in greater detail hereafter. Especially in the area of bipolar batteries, the tendency has been to create individual battery cells and to weld them together, such as by using friction or vibration welding. See, for example, U.S. Pat. No. 4,948,681 issued Aug. 14, 1990 to Zagrodnik, et al. and entitled "Terminal Electrode." In this patent, a plurality of zinc bromine cells are joined with terminal electrodes having a specific structure shown in particular in FIGS. 1 and 6-8. The individual cells and the terminal electrodes are vibration welded to one another to prevent leakage of the battery liquids. In this patent, the terminal electrodes include an injection molded frame, but there is no teaching or suggestion of using the injection molding technique to contain anything more than a single element of the battery.
Basic bipolar battery technology is described in U.S. Pat. No. 4,900,643 issued Feb. 13, 1990 to Eskra, et al. and entitled "Lead Acid Bipolar Battery Plate and Method of Making the Same." In this patent, a plastic conductive material, with a mesh of metallic wire disposed therein, is used as the substrate for the bipolar materials, the active paste material being disposed on either side thereof. In particular, the patent relates to the division of the substrate into discrete areas.
A further patent describing bipolar batteries was issued on Apr. 2, 1991 to Symanski, i.e. U.S. Pat. No. 5,004,655 entitled "Thin Bipolar Lead-Acid Battery With Individual Cell Vent." The invention of this patent relates to the containment of a bipolar battery cell in a spacer which is then covered by film sheets which extend beyond the periphery of the spacer. The spacer resembles a frame for the battery components. The film is sealed, e.g. by heat, in all areas except for a vent hole where a seal of the "duck bill" type may be provided. The patent does not relate in any manner to the use of a monolithic injection molded container for a plurality of individual battery cells.
One problem encountered in the commercialization of the bipolar battery technology has been electrolyte leakage, either from individual cells or from combined cells. In addition, the containment systems used in prior bipolar technology have not provided satisfactory support of the internal components such as separators, electrodes, spacers and substrates, resulting in plate distortion and separator damage. A system which would overcome the problems of electrolyte leakage and proper support for the bipolar battery components would represent a significant advance in the art.